spsa / sipr conference 2010 remote chemical detection by tunable lasers : potential applications in...
TRANSCRIPT
SPSA / SIPR Conference 2010
Remote Chemical Detection by
Tunable Lasers :
Potential applications in Threat
Detection and Forensics
Dr Graeme Malcolm
Acknowledgements
•Co-authors:• G.T. Maker, B.Miller & G. Robertson,
M Squared Lasers Ltd• M.H. Dunn and D.J.M Stothard,
University of St. Andrews, UK
•Co-workers :• C.R Howle, A McIntosh, L.Lee and C.Dyer• Defence Science and Technology Laboratory (DSTL),
Porton Down, UK
• Work supported by:• DSTL, MoD, Royal Society of Edinburgh, Scottish
Enterprise.
Overview
•Active IR hyperspectral sensing concept
•Source requirements
•Source & imaging system
•Results
•Threat Detection and Forensic Applications
•Conclusion and Summary
www.m2lasers.com
Introduction
•Problem: real-time detection & imaging of threat materials at safe distances• CWAs, BWAs, IEDs, TICs• Ideally detect many agents with one device• ‘Safe’ distance typically ten(s) metres
IED ThreatTypical Explosives Mass(TNT Equivalent)
Building Evacuation Distance
Pipe Bomb 2.3 kg (5 lbs) 21 m (70 ft)
Suicide Belt 4.5 kg (10 lbs) 27 m (90 ft)
LPG Tank 9 kg (20 lbs) 48 m (160 ft)
Ref: US Army, National Ground Intelligence Center, IED Safe Standoff Distances
Stand-off Concept
Confidential - Feb ‘09
•Threat Detection Concept
•M Squared Current Capability •CWA Sensing
www.m2lasers.com
Application Requirements:IR Threat Signatures
•C C•C N
•C N•C C
•C O
•X-H attached tohetero-atoms
•C-H •Triples•Doubles
•Singles
•N H •O H
•4000 •2000•3000 •1000
•2300 •2100 •1800 •1500•2800•4000 •3200
•cm-1
•5.0•2.5 •10•3.3 •µm
•cm-1
•Typical absorption wavelengths of molecular bonds in common organic molecules
Active IRHyperspectral Remote Sensing- Concept
•Use strong absorptions of target molecules or compounds in the IR waveband•Illuminate scene with IR light of high spectral purity to coincide with absorption features• Collect back-scattered light
•Target molecule/compound in path of beam will absorb and reduce backscatter• Negative Contrast Imaging
•Tunable IR source• Different absorption features
measured and spectroscopic identification possible
3.0 3.5
4.0 4.5 5.0
10 -17
10 -18
10 -19
10 -20
10 -21
10 -22
HCN
C2H2
OH
NH3
H2O
BTEX
CH3CI
C2H4
NO2
HCI
CH4
C2H6
H2CO HBr
H2SSO2
CO2
PH3
N2O
OCS
CO
GeH4
HI
C2N2
O3
Wavelength (µm)
Lin
e S
tren
gth
(cm
/mole
cu
le)
Spectroscopic survey of line strengths of in the 3-5µm infrared region
Source Requirements
•Sensitivity & specificity require sources with:• High power & brightness (for range, high SNR)• Broad wavelength tuning (cover many species)• Suitable linewidth (selectivity) • High efficiency and compactness (portability)
•Lack of suitable IR illuminators has hindered adoption of active IR hyperspectral sensing
Novel IR Illuminator - Firefly-IR
•OPO = broad tuning, dual NIR & MWIR outputs•Intracavity OPO = high efficiency•Integrated pump = compact•Designed for field use:• Maintenance-free design• Instrument Control by Ethernet• InvarianT™
alignment-free mounts
36 x 21 x 7cm (L x W X H)
Firefly-IR:Performance Characteristics
•Tuning ranges:• 1.4 - 1.8 µm (>300 mW)• 2.8 - 4.6 µm (>120 mW)•Pulse repetition rate:• Up to 300 kHz•Pulse width:• < 10 ns (FWHM)•Linewidth:• < 6 cm-1 (no étalons)• < 2 cm-1 (signal étalon)
Pump
Signal
Idler
QS Nd:YV04 pump
PPLN
(Optional étalons)
M2 < 1.4 at 3.3µm
Typical Tuning Curve - MWIR Output, Broadband
Firefly-IR + Scanner:Imaging
From Firefly-IR
MCT Detector
CaF2 Lens
Galvanometermirror
Raster :
Backscatter Absorption Gas Imaging for Gases
Active Reflectance / Absorption Imaging of Liquids/Solids
Video-Rate Imaging of Gases
Normal video:gas is invisible
What Firefly saw – methane gas
Firefly-IR + Scanner:Imaging Applications
Demonstration of gas imaging and false colour concentration measurement with Firefly-IR using differential absorption
Firefly-IR + Scanner:Concentration Resolution & range
•Sensitive CH4 monitoring
• Detection to <35 ppm.m• Real-time imaging
Identification of Liquids
Spectral fingerprinting of liquids : various mineral oils
Identification of Liquids II
•Spectroscopic & spatial negative contrast imaging of mineral oils – with differential analysis
Z ~1.2 m
www.m2lasers.com
Imaging Threat Simulants:
Forensics : Attempted to remove CWA simulant but still detectable
•Z ~1.2 m
Applications in Threat Detection / Forensics•Identifying threats• Security & venue protection• Counter Terrorism screening
•Decontamination• Identifying effective decontamination requirements
•Triage• Understanding nature of attack substance
•Forensic Investigation• Ability to investigate a scene remotely and chemically map
evidence.
THz Imaging for Drug Detection
•THz Spectral Fingerprinting
•The Importance of Terahertz:
•New spectroscopic area important for molecular identification
•Like X-rays but non-ionising – not dangerous
•Drug detection and Identification
•Leveraging pharmaceuticals Leveraging pharmaceuticals non-destructive testing / analysisnon-destructive testing / analysis
•Ecstasy
•Aspirin
•Meth
•
Summary
•Demonstrated active IR spatial/spectral detection of gases and liquids
• Gases down to 10ppm.m at >10m
• Liquids down to 20ul at 10m
• Solids down to ng of residue
•Novel laser sources provides newcapabilities for threat agent imaging with potential applications in:
• Detection of CWAs and Explosive Materials
• Counter-terrorism and forensic investigation
• Drug detection and analysis
